I am always polite to FE people. There are a variety of reasons for this, the nicest being that I actually agree that absolutely everything should be open to questioning, which means if someone is suspicious about the shape of the earth they have the right to ask questions. Those people deserve polite and accurate answers. On top of that, I think there are a lot of FE trolls that feed off of people melting down over this stuff, so rather than feed the trolls I provide very factual answers without any controversy.

That said, I personally just find the whole thing insane. I'm an engineer and a big math and physics nerd, so almost every argument sounds to me like a bad joke about physics from someone who wants to be Randall Monroe but is significantly less funny. Like, IMO Eric Dubay could be one of the best "corney jokes about bad physics" web comics ever.

A handful of FE arguments are actually semi correct and deserve a real answer. The most prolific of these is that despite what all the "believe science" shills say, you actually cannot reliably see the curve from the ground. This is just a fact of the small amount of curvature that the earth has and the interference that the earth surface atmosphere has on light propagation. So jackasses like Neal Degrasse Tyson, Professor Dave, SciManDan, etc. are all showing themselves to be clowns. Unfortunately, we just have to tell the FE people that visual measurements restricted to the ground are too noisy to reliably demonstrate earth curvature.

This is one of those examples I told you about exhibiting why almost no one takes FEers seriously. However, as is my habit, I will provide you an accurate and polite answer.

NDT is not one of "my guys," he is a celebrity who makes entertainment for the (very stupid) masses. I assume that "goalposts have to be moved" implies that all the scientists are hiding that the globe model is totally failing. In this case what they are hiding is "all the extra land in the southern hemisphere" which is of course consistent with FE. This is typical Duvey / Weiss style nonsense that uses the sloppy language of an entertainer like NDT to make an argument that sounds like it makes sense if you don't know anything about the topic.

TLDR: The "pear" you are referring to is a north pole / south pole difference on the order of 0.000007, not some "secret failure of the globe that the world elite are hiding." Flat earthers finding problems in things like NDT popular interviews is not an argument. If you want to be taken seriously, find a major flaw in modern geodesy.

A long time ago, astronomical observations (i.e. the sun, the stars, etc.) suggested that the earth is round and rotating. The simplest model, then, is a sphere, and rudimentary measurements converge on a rough figure of a sphere of 4000 mile radius. Once a system of mechanics and gravitation was worked out, it was clear that a spinning body under self gravitation must be an oblate speroid. Improved measurements did in fact confirm that the equatorial radius is about 13.4 miles larger than the polar, giving a flattening of about 1/298.2 (~0.00335). The so called "pear shape" in this NDT video is a finding initially from the first satellite orbits in the 1950s. As you can read for yourself, modern measurements put this at a 148 foot difference between the distance to the north pole and the south pole from the center. Compared to the "theoretical polar radius" this is a "pear shape" on the order of ~0.000007. It has also been found that the equator is not circular to a similar order of magnitude. Nowadays, everything is done using the reference ellipsoid and the geoid.